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Old September 3, 2012, 01:28 PM   #1
tyyota
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Excessive Velocity in Redhawk

My Ruger Redhawk 44 mag with 7.5" barrel is getting some very impressive velocities with both factory and handloads. I am very suprized by how much over the book specs this gun is producing:

Hornady 240ga xtp (factory load) - book velocity 1350 - actual 1500
Hornady 300gr xtp (factory load) - book velocity 1150 - actual 1330Winchester 240ga SP (factory load) - book velocity 1180 - acutal 1500

Sierra 300gr SP over 2400 (handloads):
@17.0gr - acutal 1170
@18.0gr - actaul 1260
@18.5gr - actual 1300
@19.0gr - book 1050 - actual 1320

Brass is not showing any signs of excess pressure. The primers are getting flat but nothing out of the normal. I have showed the brass to two other experienced handloaders and both agree they look fine. Extraction from the cylinder is slick.

I am shooting over a F1 Shooting Chrony that I have verified its accuarcy with another gun shooting two different types of ammo - it spot on for factory cci 22LR.

Do I have any reason to be concerned or am I (as one person told me) lucky to have a fast barrel?

T
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Old September 3, 2012, 01:32 PM   #2
Rifleman1776
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Flat primers a warning sign.
Those velocities are impressive. I never had a chrony.
Those 300 gr. bullet velocities would be stoppers for anything.
Painful shooting though. For me, a shooting 'session' with 300 gr. bullets and max-max loads was one cylinder, six shots.
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Old September 3, 2012, 01:38 PM   #3
ScottRiqui
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What length barrel was used to generate the velocities listed in the load manual? An extra 2-3 inches of barrel length can make a *big* difference in handgun velocities.
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Old September 3, 2012, 01:58 PM   #4
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A handgun cartridge can gain 100 fps (more or less) per inch of added barrel length (to a point of diminishing and then reversal of returns), so if you're comparing your 7.5" velocities to those from a 5-6" revolver, the increase in velocity makes perfect sense.
There can also be dimensional variances in cylinder gap, forcing cone and barrel land/groove diameter that, although you'd think not much of a control, can account for some of the velocity increase.

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Old September 3, 2012, 02:22 PM   #5
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All the above are good advice, in my opinion.

If your chronograph is too close to the muzzle, you can get faster velocities, as it may be reading the muzzle blast, but that is highly unlikely in this case, as such mis-readings are most always HIGHLY erratic.

If there is another 44 Mag gun around, you might try shooting both guns with the same ammunition over the same setup.

The "fast barrel" conjecture looks likely at this point.

Lost Sheep

p.s. for more information about barrel length and velocity, check out the site "ballistics by the inch"
http://www.ballisticsbytheinch.com/
started by a couple of guys with an intense curiosity and enough time on their hands to satisfy it, and a LOT of lead.
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Old September 3, 2012, 02:32 PM   #6
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I get higher than book velocities with my 44 Mag RH also. Mine is 7.5" and the books usually use a 4" barrel for testing. Forcing cone and chamber dimensions may well help it also.

Be happy about it. You can run lower pressure ammo (usually more accurate) with maximum results. While the guys with 4" barrels are shooting their one cylinderful of Buffalo Bore ammo for the day, you'll be breaking out your 3rd box of 50 (lol) and besting them through less recoil and just as much (practical) velocity.

Time to buy a mould! RHs love lead.
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Old September 3, 2012, 03:53 PM   #7
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It is not unusual for new guns/barrels to shoot faster than older ones that have seen a lot of hot loads. Wear seems to reduce pressures and velocities for some reason(s). I don't remember where I read it, but one of my loading manuals has an example of a .357 magnum that lost something like 100 to 200 fps off its hot loads during an extensive testing program.

SO, shooting those hot loads a lot may get you slower loads in the future.

As for the actual pressures, I looked at QuickLOAD. It is not easy to tune QuickLOAD for revolvers, and I was not able (with the little effort I have time for right now) to produce the same load vs velocity curve that you show for the Sierra 300 grain bullet. So, the following results are not really definitive. However, QuickLOAD seems to think that 1320 fps is quite possible with a 7.5" barrel (+1.62" cylinder an no gap) with 18.5 grains of 2400. I had to adjust the case volume quite a bit to get the velocities that low, and the resulting pressures were well below SAAMI limits. I did not use the 19.0 grain load because velocity increase with charge increase seems to be dropping off a lot by that point. The loading density for the 18.5 grain load was only 71% to get the velocity to the point that you measured. But, it is usual to have to increase the case capacity of straight-walled revolver cartridges in QuickLOAD by a substantial value to make it match velocities. I don't really know the answer to the question about whether that also makes it match pressure.

Perhaps Unclenick can add something from his superior knowledge of QuickLOAD.

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Old September 3, 2012, 06:29 PM   #8
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Thank you for the tips so far!
FYI I don't know what Hornady or Winchester use for posted velocities with the factory ammo. For the Sierra handloads the manual says they used a Blackhawk with a 7.5" barrel. The 300 Sierras were loaded at 1.715 OAL, just a touch shorter than the books 1.735. I doubt the extra 200 fps is coming from the extra .020" squish.
Due to the fact that the extra velocity is present with factory loads make me less concerned that the handloads are dangerous - I believe that most stock ammo is loaded with a certain modesty.
I first suspected the chrony but I did check it againts two different factory loads of CCI 22LR from a 10-22. I checked the 44 on two differnt days at two different muzzle distances. I highly doubt the chrony is out.
I think for the 300 grainers I am going to stick with 18.0 grains (a safety margin below the posted max 19.0) and live with the extra speed.
T
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Old September 3, 2012, 09:17 PM   #9
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I'd shoot the same ammo in a different 44. Be sure that your first screen is no closer than 15ft. My Oehler has a setting for the distance to the first screen. Even with a very tight throat, 200fps is a stretch if the loads are within specs. If you're getting 1500 from WW factory 240s, I'd really dig deeper.
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Old September 4, 2012, 11:49 AM   #10
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I agree with GeauxTide--an inch or two of extra barrel length doesn't explain that wide of a velocity difference. You're definitely right to question what's going on, Tyyota.

A lot of what is typically looked at for pressure signs in handguns can be really misleading. If your revolver has tight chambers, your brass could still last a very long time and not show any issues, even with scary high pressures. Along with tight chambers, add nice smooth chamber walls and you may not ever feel sticky extraction before pressures get high enough for the cylinder to let go. The end result with such a combination is that it's possible to be at fairly dangerous pressure levels and not even know it. I'm not saying that's what's happening in your case, but it's something to keep in mind.

If you can find someone else with a chrony, see if you can shoot a few strings over it and compare the results with those from your own chrony, just to see how close they are.

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Old September 6, 2012, 10:51 PM   #11
Edward429451
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This is an interesting thread and since I own the same gun (7.5" RH) I thought I'd take a closer look at exactly what I'm getting as compared to the OPs numbers and perhaps we'll be able to see some correlation here. I've always been aware of my higher than expected velocities from my RH and was blissfully ignorant that it could even be a potential problem. Like the OP, I've never had sticky extraction from my RH or anything beyond a little flattening of the primers. Considering the test barrel length of 4", I still don't think there's a problem, but there are greater minds than I so I'll throw this data out there for your perusal.

Some of my loads vs book velocities are shown. My Lyman #48 shows a 4" test barrel. Book velocities are shown in parenthesis ().

245 gr Keith (Lyman #429421)
2400

17.0 1209 FPS (below book startload of 18.5gr for 1087fps)
18.0 1274 FPS (see above)
19.0 1287 FPS (book max is 20.6gr for 1248 FPS)

H-110
24.0 1448 FPS (1218 FPS)

Unique
8.0 953 FPS (below book startload of 9.8 for 912 FPS)

255 gr SWCGC (Lee. Very similar to Lyman 429244 in book)
H-110

21.8 1377 FPS (1097 FPS)
22.0 1417 FPS (max is 22.8 for 1186 FPS)

I have other data, but for other guns, boolits and such so did not list those. I get even higher velocities with some of these loads in my SBH!.
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Old September 7, 2012, 04:18 AM   #12
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Ruger's stainless barrels (on revolvers, in particular) are considered to be some of the hardest barrels around. Once they are broken in, they tend to have a great bore surface.

If the test loads were developed in something else (such as the 7.5" Blackhawk), it could help explain the disparity in velocities.
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Old September 7, 2012, 11:54 AM   #13
Edward429451
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My RH is blue, but I did condition the bore a couple few times with JB Bore Paste. I wont run jacketed thru it at all any more.

How's that for a twist?! Most guys wont touch lead, I wont touch jacketed.
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Old September 16, 2012, 10:19 PM   #14
tyyota
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So I finally got back to the range to confirm some data. I was able to do some testing with another 44 RedHawk - this one a 9.5" barrel (mine is 7.5").
I moved the chrony out further (5 yard) to eliminate muzzle blast.

Winchester 240gr SP (Factory):
My 7.5" RH - 1540 fps (Book Value 1180 with 4" Barrel)
9.5" RH - 1470 fps

Sierra 300gr SP (over 18.0gr 2400)
My 7.5" RH - 1250 fps (Book Value around 1000 fps with 7.5" Barrel)
9.5" RH - 1140 fps

Hornady 240gr XTP (over 19.5gr 2400)
My 7.5" RH - 1350 fps (Book Value 1240 with 7.5" Barrel)
9.5" RH - 1280 fps

Hornady 240 XTP (over 20.5gr 2400)
My 7.5" RH - 1420 (Book Value 1310 with 7.5" Barrel)

It seems that my 7.5" barrel is producing velocities of about 70-100 fps faster than a 9.5" barrel.
Also it is producing velocities of about 100-200 fps faster than book values.
Both guns were showing similar signs at the primer - mild to moderate primer flattening. The 9.5" gun is a very "experienced gun". Mine is of 80's vintage but was first shot by me a year and a half ago.

And I shot some of the same handloads out of my Rossi 92 16" barrel and got more or less dead on book values.

I did some shots to compare Winchester brass to Hornady - with the same load in each case I was getting about 50 fps more with Hornady.

So the lingering questions are: how, why, and is this all safe?
Is the fast gun phenomenon true?

T
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Old September 17, 2012, 01:56 PM   #15
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It would be nice to know what the velocities are in a SAAMI-spec test barrel. That is about the only way to know if your barrel is one of the "fastest" or if, instead, it is somehow producing higher-than-SAAMI pressures to get the higher velocity.

There is a table of velocities for thirty-one .357 Magnum barrels, each with three different bullets/loads in Speer Manual #14. I am not going to try to type it out here, but for the 9 revolvers with 6" barrels, the velocity spread was 1277 to 1603 fps for the 125 grain bullet, 1142 to 1417 for the 140 grain bullet, and 1002 to1284 for the 158 grain bullet. The 10" Contender barrel gave about the same velocities as the SAAMI test barrel, but each is a sample of one, so that may not always be true in other guns. An 8-3/8" S&W (which is about a 10" total barrel length with a gap) gave 1501, 1342, and 1221 fps for the three different bullets. So, it was not as fast as the fastest 6" barrel, and substantially slower than the SAAMI barrel.

So, from that, I would say that you Redhawk probably should not be exceeding the velocity of the same round from a (new) 10" Contender barrel unless it is exceeding SAAMI pressures.

Is there anybody here who has data for the OP's loads in a 10" Contender barrel?

The caveat is that pressure-vs-time curves for revolvers and test barrels apparently look substantially different in shape, based on some earlier experiments by Speer where they instrumented an actual revolver. So, just about every comparison that we can make is already "apples-to-oranges."

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Old September 17, 2012, 09:27 PM   #16
tyyota
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I havent slugged the barrel yet but I just checked the cylinder gap and found it to be about .005"

T
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Old September 18, 2012, 08:01 AM   #17
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clear english

Quote:
Is the fast gun phenomenon true?
The "fast gun" is no phenom; it is a regularly observable reality.

I like fast guns, because they give me more room, more safety margin.
Me.
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Old September 18, 2012, 09:43 AM   #18
Edward429451
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So could there be something about the RH's that make them faster across the board. Apparently I have a fast RH also. Could this mean that most RHs are fast?
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Old October 3, 2012, 08:37 PM   #19
tyyota
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So I finally got the opertunity to slug my RH: measureing the 3 positions of opposed groves I get between .4300 - .4305
So that looks to be entirly normal, no?
T
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Old October 4, 2012, 06:57 AM   #20
SL1
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SAAMI drawings

show the groove diameter as 0.429" with a 0.004" positive tolerance and zero negative tolerance. So, your groove measurements appear to be normal.

A more significant measurement might be bore cross sectional area. That is tha actual open area in the barrel that the bullet must be squeezed into. SAAMI specifies 0.1405 square inches.

You can calculate it pretty well as the groove diameter squared, divided by 4 and multiplied by Pi then subtracting the area taken by the lands. That is the height of the lands (or the depth of the grooves) multiplied by the width of the lands times the number of lands.

The smaller the area, the higher the pressure and thus velocity.

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